I posted a couple of days ago that Americredit agreed to remove the 30 day late notation from my auto loan. The late was from March 2000. This had a surprisingly small effect on my score today when Experian (Credit Expert) updated. My score before was 617 and is now 620.
What does the rest of your credit look like? If you have lots of positives or negatives to "drown it out", it may have a small impact on your overall score.